Anomalous Transport Signatures in Weyl Semimetals with Point Defects.

We present the first theoretical study of transport properties of Weyl semimetals with point defects. Focusing on a class of time-reversal symmetric Weyl lattice models, we show that dilute lattice vacancies induce a finite density of quasilocalized states at and near the nodal energy, causing strong modifications to the low-energy spectrum. This generates novel transport effects, namely, (i) an oscillatory behavior of the dc conductivity with the charge carrier density in the absence of magnetic fields, and (ii) a plateau-shaped dissipative optical response for photon frequencies below the interband threshold, E_{F}≲ℏω≲2E_{F}. Our results provide a path to engineer unconventional quantum transport effects in Weyl semimetals by means of common point defects.

Biocompatibility, induction of mineralization and antimicrobial activity of experimental intracanal pastes based on glass and glass-ceramic materials.

AIM: To evaluate the biocompatibility, induction of mineralization and antimicrobial activity of experimental intracanal pastes based on two glass and glass-ceramic materials. Calcium hydroxide (Ca(OH)2 ) paste was used as the positive control. METHODOLOGY: The glass-ceramic powder [two-phased Biosilicate (BS-2P)] and F18 bioactive glass were mixed with distilled water (ratio 2 : 1), inserted in polyethylene tubes and implanted in the subcutaneous tissues of 16 rats. Empty tubes were used as negative control. After 7 and 30 days (n = 8), the rats were euthanized for haematoxylin-eosin, von Kossa, polarized light and osteopontin (OPN) immunolabeling analysis. Direct contact tests using a suspension of each paste were performed with Enterococcus faecalis planktonic cells to evaluate antimicrobial activity (24 h of contact), in a pilot study. The number of CFU mL-1 was calculated for each group. The antimicrobial analysis data were submitted to one-way anova and Tukey tests, whilst biocompatibility and immunohistochemical data were submitted to the Kruskal-Wallis and Dunn tests (P < 0.05). RESULTS: Most specimens of the control, BS-2P and Ca(OH)2 groups were associated with moderate inflammation seven days following implantation, whilst F18 was associated with moderate to severe inflammation, without differences amongst the groups (P > 0.05). At 30 days, most specimens of control, F18 and BS-2P groups had mild inflammation, whilst Ca(OH)2 had mild to moderate inflammation; however, no differences were determined amongst the groups (P > 0.05). The fibrous capsule was thick at 7 days, becoming thin at 30 days. All pastes induced von Kossa-positive structures and were birefringent to polarized light. At seven days, the BS-2P group had significantly more OPN immunolabeling compared to the control and Ca(OH)2 groups (P < 0.05). At 30 days, the F18 group had significantly more OPN immunolabeling compared to the control and Ca(OH)2 groups (P < 0.05). All pastes reduced the total number of E. faecalis; however, the reduction was only significant when comparing BS-2P and Ca(OH)2 groups to the control (P < 0.05). Only calcium hydroxide eliminated E. faecalis. CONCLUSIONS: Experimental BS-2P and F18 pastes were biocompatible, stimulated biomineralization and induced significant OPN immunolabeling compared to Ca(OH)2 . Only the BS-2P paste demonstrated antimicrobial activity comparable to Ca(OH)2 .

A leg ulcer with hard, yellow projections.

Gout is a multisystem disease that may present in different ways. We report an elderly man who presented with a large ulcer of the left leg with hard yellow projections evolving for one year. Analytical study revealed a normal uric acid level, but histopathology showed a focal basophilic acellular material compatible with a gouty tophus. This tophus represents the cardinal feature of advanced gout and may present several challenges to wound care professionals. In fact, the ulcer in our patient persisted after one-year follow-up. Our aim is to alert clinicians about a rare cutaneous presentation of gout that may be increasingly diagnosed.

The presence of osteocalcin, osteopontin and reactive oxygen species-positive cells in pulp tissue after dental bleaching.

AIM: To analyse the influence of H2 O2 on pulp repair through osteocalcin and osteopontin immunolabelling and in cellular defence by using the antireactive oxygen species (ROS) antibody. METHODOLOGY: The maxillary molars of 50 rats were treated with 35% H2 O2 (Ble groups) or placebo gel (control groups). At 0 h and 2, 7, 15 and 30 days (n = 10 hemimaxillae), the rats were killed and pulp tissue was evaluated using inflammation and immunolabelling scores (osteocalcin/osteopontin); ROS-positive cells were counted. Paired t-test and Wilcoxon signed-rank test were used (P < 0.05). RESULTS: The Ble group had necrosis in the coronal pulp at 0 h and in the occlusal third of the coronal pulp at 2 days; at 7, 15 and 30 days, no inflammation was noted similar to the controls (P > 0.05). Osteocalcin was absent in the Ble at 0 h, moderate at 2 days and increased thereafter, differing from the controls at all two periods (P < 0.05). Osteopontin was higher principally at 7 and 15 days in Ble groups, but differing with control groups from 2 days after bleaching (P < 0.05). The Ble group had more ROS-positive cells in the pulp at 7 and 15 days (P < 0.05). Tertiary dentine was observed at 7 days, increasing thereafter (P < 0.05). CONCLUSIONS: Post-bleaching pulp repair was associated with increased osteocalcin over time. Osteopontin also participated in this process, and anti-ROS was involved in cellular defence against H2 O2 .

In vivo analysis of the presence of heme oxygenase-1, transcription factor Jun-D and CD90+/CD73+/CD105+/CD45- cells in the pulp of bleached teeth.

AIM: To investigate hydrogen peroxide (H2 O2 )-induced responsiveness in pulp cells using heme oxygenase-1 (HO-1) immunolabelling, Jun-D immunolabelling to study the effects of H2 O2 on odontoblastic differentiation and CD90+/CD73+/CD105+/CD45- cell counting for in vivo identification of mesenchymal stem cells in the pulp. METHODOLOGY: The maxillary molars of 50 rats were treated with a bleaching gel (35% H2 O2 , 1 × 30 min) or placebo gel (control groups). At 2, 3, 7, 15 and 30 days after the treatment (n = 10), inflammation in pulp tissue was analysed by haematoxylin-eosin staining, HO-1- and Jun-D-immunolabelled cells were counted in each third of the pulp chamber, and the number of CD90+/CD73+/CD105+/CD45- cells was quantified by immunofluorescence. The results were assessed using the Paired t-test or Wilcoxon signed-rank test (P < 0.05). RESULTS: Significant H2 O2 -induced inflammation was noted at 2 and 3 days (P < 0.05), with tertiary dentine formation occurring from 7 days. The bleached specimens had greater HO-1 immunolabelling in the middle and cervical thirds of the coronal pulp at 2 and 3 days, in all thirds at 7 days, and in the occlusal third at 15 days (P < 0.05), and significant nuclear Jun-D immunolabelling in the cervical third at 2 and 3 days and in the occlusal and middle thirds at 7 days (P < 0.05). Bleached and control groups had low numbers of CD90+/CD73+/CD105+/CD45- cells in the pulp at all periods (P > 0.05). CONCLUSIONS: Pulp cells responded to oxidative stress by expressing HO-1 during the post-bleaching inflammation phase until the beginning of the repair phase. Jun-D expression occurred during the reduction of inflammation and the beginning of tertiary dentine production. The presence of oxidative stress did not influence the number of CD90+/CD73+/CD105+/CD45- cells identified in vivo in the dental pulp.

Perianal purpuric plaques revealing an amyloid light-chain amyloidosis: case report and review of the literature.

Systemic immunoglobulin light chain amyloidosis is the most common and severe type of amyloidosis. There is an abnormal fibrillary protein deposition in tissues that leads to progressive and irreversible organ dysfunction. The most commonly affected organs are kidney and heart. Although rare, cutaneous manifestations may be the first clinical sign of the disease and usually present as hemorrhagic lesions, such as purpura, petechiae, and ecchymosis. We present a 71-year-old man that presented to our department because of exuberant purpuric plaques in the anogenital area as the first manifestation of an amyloid light-chain (AL) amyloidosis. The multi-organ involvement in addition to rapid clinical deterioration precipitated the patient's death four months later.

Injury of primary afferent neurons may contribute to osteoarthritis induced pain: an experimental study using the collagenase model in rats.

OBJECTIVE: Pain exacerbated by movement and loading on the joint is the major symptom of osteoarthritis (OA), but the mechanisms of chronic pain in this pathology are still poorly understood. Using the intra-articular (i.a.) injection of collagenase in the knee of rats as a model of OA, we aimed at evaluating whether injury of sensory neurons may contribute to the development of OA-associated nociception. DESIGN: OA was induced by i.a. injection of collagenase into the left knee joint of adult male Wistar rats. Histopathological changes and movement and loading-induced nociception were assessed for 6 weeks. A time-course analysis of the expression of the neuronal injury markers activating transcription factor-3 (ATF-3) and neuropeptide Y (NPY) and of the neuropeptide SP in the dorsal root ganglion (DRG) was performed. Gabapentin's effect on nociception was evaluated, as well as the expression of the α2δ-1 voltage-gated calcium channel subunit. RESULTS: Collagenase induced the development of OA-like histopathological changes and of movement-induced nociception. Altered expression of ATF-3, NPY and SP was observed in the DRG, correlating with the degree of articular degeneration after 6 weeks of disease progression. Repeated administration of gabapentin reversed the nociceptive responses 6 weeks after the induction of OA. α2δ-1 was upregulated in the DRG. CONCLUSION: By inducing nociceptive behaviours associated with relevant joint structural changes, the i.a. injection of collagenase presents itself as a pertinent model for the study of OA pain. The findings in this study support the hypothesis that injury of sensory neurons innervating OA joints may be a significant element in the mechanisms of OA-associated pain.

Monte Carlo sampling in fractal landscapes.

We design a random walk to explore fractal landscapes such as those describing chaotic transients in dynamical systems. We show that the random walk moves efficiently only when its step length depends on the height of the landscape via the largest Lyapunov exponent of the chaotic system. We propose a generalization of the Wang-Landau algorithm which constructs not only the density of states (transient time distribution) but also the correct step length. As a result, we obtain a flat-histogram Monte Carlo method which samples fractal landscapes in polynomial time, a dramatic improvement over the exponential scaling of traditional uniform-sampling methods. Our results are not limited by the dimensionality of the landscape and are confirmed numerically in chaotic systems with up to 30 dimensions.

Supramolecular porphyrin as an improved photocatalyst for chloroform decomposition.

In this work, the outlying decoration of the free-base meso-(4-tetra) pyridyl porphyrin (H2TPyP) with the RuCl(dppb)(5,5'-Me-bipy) ruthenium complex (here named Supra-H2TPyP) is observed as an improved molecular photocatalyst for dye-mediated chloroform (CHCl3) decomposition via one-photon absorption operating in the visible spectral range (532 nm and 645 nm). Supra-H2TPyP offers a better option for CHCl3 photodecomposition when compared to the same process mediated by pristine H2TPyP, which requires either excited-state- or UV absorption. The chloroform photodecomposition rates for Supra-H2TPyP as well as its excitation mechanisms are explored as a function of distinct laser irradiation conditions.

Nonlinear optical conductivity of a two-band crystal I.

The structure of the electronic nonlinear optical conductivity is elucidated in a detailed study of the time-reversal symmetric two-band model. The nonlinear conductivity is decomposed as a sum of contributions related with different regions of the first Brillouin zone, defined by single or multiphoton resonances. All contributions are written in terms of the same integrals, which contain all information specific to the particular model under study. In this way, ready-to-use formulas are provided that reduce the often tedious calculations of the second and third order optical conductivity to the evaluation of a small set of similar integrals. In the scenario where charge carriers are present prior to optical excitation, Fermi surface contributions must also be considered and are shown to have an universal frequency dependence, tunable by doping. General characteristics are made evident in this type of resonance-based analysis: the existence of step functions that determine the chemical potential dependence of electron-hole symmetric insulators; the determination of the imaginary part by Hilbert transforms, simpler than those of the nonlinear Kramers-Krönig relations; the absence of Drude peaks in the diagonal elements of the second order conductivity, among others. As examples, analytical expressions are derived for the nonlinear conductivities of some simple systems: a very basic model of direct gap semiconductors and the Dirac fermions of monolayer graphene.

Central Pain in Parkinson's Disease: Behavioral and Cognitive Characteristics.

INTRODUCTION: Pain is a major nonmotor symptom of Parkinson's disease (PD), and central parkinsonian pain is the core feature of the putative Park pain subtype of PD. This study aimed to explore the cognitive and behavioral profile of PD patients with central parkinsonian pain. Material and Methods. A structured interview was used to identify and characterize pain in a cohort of 260 consecutive PD patients. The Ford classification of pain was applied. The Dementia Rating Scale-2 (DRS-2) and the Impulse Control Disorders in Parkinson's Disease Short Form (QUIP-S) were administered, and patients' smoking habits were recorded. The Unified Parkinson's Disease Rating Scale (UPDRS) was used to assess motor and nonmotor symptoms in off and on conditions. RESULTS: One hundred and eighty-eight patients (68%) reported pain; and in 41 (22%) of them, the pain was classified as central parkinsonian pain. PD patients with central parkinsonian pain had better cognitive performance in DRS-2 Initiation/Perseveration and Conceptualization subscales but reported more other compulsive behaviors (e.g., hobbyism, punding, and walkabout) and had more current smoking habits than those without pain or with non-central parkinsonian pain. Multiple logistic regression analyses revealed that the DRS-2 Conceptualization subscale, other compulsive behaviors, and smoking habits remained statistically associated with central parkinsonian pain even when other significant covariates were considered. Only patients with pain, regardless of type, had a gambling disorder. Discussion. The study results provide further evidence that pain revealed that patients with central parkinsonian pain are more likely to present compulsive or addictive behaviors, despite having more preserved cognitive performance. Patients with central parkinsonian pain appear to have a distinct phenotype of PD.

Basis-independent spectral methods for non-linear optical response in arbitrary tight-binding models.

In this paper, we developed a basis-independent perturbative method for calculating the non-linear optical response of arbitrary non-interacting tight-binding models. Our method is based on the non-equilibrium Keldysh formalism and allows an efficient numerical implementation within the framework of the kernel polynomial method for systems which are not required to be translation-invariant. Some proof-of-concept results of the second-order optical conductivity are presented for the special case of gapped graphene with vacancies and an on-site Anderson disordered potential.

Photophysics and visible light photodissociation of supramolecular meso-tetra(4-pyridyl) porphyrin/RuCl2(CO)(PPh3)2 structures.

In the last decades, supramolecular structures have been explored in many technological efforts. One example of such supramolecules is attained when ruthenium complexes are attached in the outer sites of a porphyrin. Ruthenium complexes act as modulators of the photophysical processes of macrocyclic molecules. Besides the investigation of the main changes introduced by the ruthenium complexes in the electronic and vibronic properties, and in the excited state deactivation processes of porphyrins, discussions concerning the photostability of these supramolecules are much needed. Here, we investigate the supramolecular free-base meso-tetra(4-pyridyl) porphyrin decorated with "RuCl2(CO)(PPh3)2" ruthenium species linked at each of its (4-pyridyl) moieties. The modifications in the photophysical processes introduced by the metallic outlying species are discussed and our results suggest an energy transfer process from the porphyrin B-band to the ruthenium complex MLCT-band. The demonstration of visible light photodissociation of the supramolecule, via both pulsed and continuous laser, is also addressed.

A study of the nonlinear optical response of the plain graphene and gapped graphene monolayers beyond the Dirac approximation.

In this work, we present numerical results for the second and third order conductivities of the plain graphene and gapped graphene monolayers associated with the second and third harmonic generation, the optical rectification and the optical Kerr effect. The frequencies considered here range from the microwave to the ultraviolet portion of the spectrum, the latter end of which had not yet been studied. These calculations are performed in the velocity gauge and directly address the components of the conductivity tensor. In the velocity gauge, the radiation field is represented by a power series in the vector potential, and we discuss a very efficient way of calculating its coefficients in the context of tight-binding models.

On the excitation dependence of fluorescence spectra of meso-tetrapyridyl zinc (II) porphyrin and its relation with hydrogen bonding and outlying decoration.

Zinc porphyrins are potential candidates for boosting the advancement of various technological applications, including those exploring the molecule's radiative emissions. In this work, the excitation dependence of fluorescence spectra from 5,10,15,20-meso-tetrapyridyl zinc(II) porphyrin dissolved in a binary solvent mixture of CHCl3: MeOH, is reported. Important modifications in the profiles of the fluorescence bands are observed after exciting the molecules in a broad wavelength range from 350 to 565 nm. We attribute such modifications to the existence of two distinct relaxation pathways, related to two quasi-degenerated potential energy surfaces (PES) in the ZnTPyP's first excited state whose population rates changes for different excitation wavelengths. We also observed that by changing the CHCl3:MeOH proportion in the binary mixture, a quenching mechanism mediated by the MeOH hydrogen bondings and ZnTPyP takes place, which allows for tuning the excitation dependence of the aforementioned relaxations pathways. Moreover, our data confirm that the addition of outlying RuCl(dppb)(bipy) ruthenium complex linked to the pyridyl moieties of the ZnTPyP ring is also an excellent strategy to modify the excitation dependence of the fluorescence relaxation pathways.

Influence of the meso-substituents on the spectral features of free-base porphyrin.

The role of meso-substituents on the spectral features of free-base porphyrins is explored. Meso-tetra(4-pyridyl)porphyrin is compared with meso-tetra(2-thienyl)porphyrin and meso-tetra(pentafluorophenyl)porphyrin. Our results indicate that some of the asymmetric Q-bands in the free-base porphyrin tend to become symmetric relative to the adopted meso-substituent. The results show that the outlying perturbations lead the free-base quasi-degenerated Qx1, Qx2, Qy1, and Qy2 bands to be closer in energy. Combined, absorption, fluorescence and Raman spectroscopies endorse our conclusions showing that both the frequencies and the Huang-Rhys factors associated with every vibronic progression are noticeably affected by the investigated meso-substituents. Our results confirm that the B-band is also multi-featured in agreement with what is found for the Q-bands.

Brain MR Imaging of Patients with Perinatal Chikungunya Virus Infection.

Since 2005, it has been known that mother-to-child transmission of the chikungunya virus is possible. Transmission generally occurs in the perinatal period. In the present study, we describe the brain lesions seen on MR imaging of 6 cases of perinatal chikungunya infection. Patients who underwent brain MR imaging in the acute phase presented with areas of restricted diffusion in the white matter, suggesting a perivascular distribution, whereas those in the subacute/late phase showed cystic lesions, also with a perivascular distribution, with or without brain atrophy. One patient also presented with scattered hemorrhages in the frontal and parietal lobes. Important differential diagnoses include rotavirus, Parechovirus, herpes simplex infection, and hypoxic-ischemic encephalopathy, depending on the disease phase.

Erratum to "Gastroenteropancreatic Neuroendocrine Neoplasia Characterization in Portugal: Results from the NETs Study Group of the Portuguese Society of Endocrinology, Diabetes and Metabolism".

[This corrects the article DOI: 10.1155/2019/4518742.].

Expression, mutation and copy number analysis of platelet-derived growth factor receptor A (PDGFRA) and its ligand PDGFA in gliomas.

BACKGROUND: Malignant gliomas are the most prevalent type of primary brain tumours but the therapeutic armamentarium for these tumours is limited. Platelet-derived growth factor (PDGF) signalling has been shown to be a key regulator of glioma development. Clinical trials evaluating the efficacy of anti-PDGFRA therapies on gliomas are ongoing. In this study, we intended to analyse the expression of PDGFA and its receptor PDGFRA, as well as the underlying genetic (mutations and amplification) mechanisms driving their expression in a large series of human gliomas. METHODS: PDGFA and PDGFRA expression was evaluated by immunohistochemistry in a series of 160 gliomas of distinct World Health Organization (WHO) malignancy grade. PDGFRA-activating gene mutations (exons 12, 18 and 23) were assessed in a subset of 86 cases by PCR-single-strand conformational polymorphism (PCR-SSCP), followed by direct sequencing. PDGFRA gene amplification analysis was performed in 57 cases by quantitative real-time PCR (QPCR) and further validated in a subset of cases by chromogenic in situ hybridisation (CISH) and microarray-based comparative genomic hybridisation (aCGH). RESULTS: PDGFA and PDGFRA expression was found in 81.2% (130 out of 160) and 29.6% (48 out of 160) of gliomas, respectively. Its expression was significantly correlated with histological type of the tumours; however, no significant association between the expression of the ligand and its receptor was observed. The absence of PDGFA expression was significantly associated with the age of patients and with poor prognosis. Although PDGFRA gene-activating mutations were not found, PDGFRA gene amplification was observed in 21.1% (12 out of 57) of gliomas. No association was found between the presence of PDGFRA gene amplification and expression, excepting for grade II diffuse astrocytomas. CONCLUSION: The concurrent expression of PDGFA and PDGFRA in different subtypes of gliomas, reinforce the recognised significance of this signalling pathway in gliomas. PDGFRA gene amplification rather than gene mutation may be the underlying genetic mechanism driving PDGFRA overexpression in a portion of gliomas. Taken together, our results could provide in the future a molecular basis for PDGFRA-targeted therapies in gliomas.